Book Review: How Radio Astronomy Made the Invisible Visible

Karl Jansky had just graduated from college as a radio engineer when he began work at the famed Bell Telephone Laboratories in 1928. Bell had built a transatlantic phone capability, but the system had a problem: It buzzed with static. If the company was going to charge callers as much as it wanted, the connection needed to be pure.

Some of the static’s sources were easily traced — interference from electrical equipment, for instance. But, as Emma Chapman writes in “The Echoing Universe: How Radio Astronomy Helps Us See the Invisible Cosmos,” “among the hums and crackles was a persistent hiss, one that defied explanation.” Finding the explanation was the young Jansky’s job.

So he built an antenna to try to pinpoint the source of the problem, an instrument Chapman calls “a tangle of wood and wire.” After more than a year of work, Jansky got an answer: The hiss came from the sky — from the constellation Sagittarius, where the center of our galaxy sits.

Through this telephone project, Jansky unwittingly became the founder of radio astronomy, the first to discover the universe emits radio waves. His tale appears at the start of “The Echoing Universe” not just as an origin story but as one that typifies the picture that Chapman paints of radio astronomy: DIY instruments, secrets accidentally uncovered, and persistent connections to Earth.

Optical astronomy is the easy astronomy to like. It reveals how the universe looks in visible light, which our eyes can see, and produces pretty pictures. Early in the book, Chapman, an astrophysicist and Royal Society Research Fellow at the University of Nottingham, likens it to an apple: “There is no preparation needed in order to enjoy it.”

Since human eyes can’t see radio waves, it’s harder to understand them intuitively, but they do something crucial that optical astronomy doesn’t: They reveal parts of the universe that would remain hidden and invisible if not for astronomers’ tangles of wood and wire. Radio astronomy, writes Chapman, is thus more lemon than apple. “Eating lemons requires tools and ingredients: a knife, a juicer, extra sugar,” she writes. “But what versatility, what promise!”

In the course of “The Echoing Universe,” the author, who as an astronomer specializes in studying the cosmos’ first stars, demonstrates the ways that radio astronomy has delivered on its promise (beyond helping Bell with its phones). Radio astronomy revealed, for instance, that the Apollo 11 lander wouldn’t sink on the moon’s surface when it arrived in 1969, and discovered the first planet outside the solar system, orbiting an exotic dead star that was invisible to optical telescopes. With engaging, humorous language and down-to-Earth explanations, she makes the invisible universe, and the people who study it, visibly vivid.

Chapman cuts the book into three parts, going from close and familiar to farther away and more abstract. Each section’s chapters detail how radio astronomy has contributed to human knowledge of things like the sun, Mars, black holes, neutron stars, the search for life elsewhere, and the mysterious dark matter and dark energy in the universe.

The chapters’ similar structure helps keep the reader grounded. Helpful in that effort, too, is that each begins with familiar descriptions. For instance, Chapman describes seeing the Milky Way with her eyes for the first time on a Yellowstone camping trip — before discussing how radio astronomers can use the Doppler shift to map the galaxy’s spiral arms.

She also grounds the more heady chapters in specific places and objects, rather than simply discussing them as concepts. For instance, the section on gravitational waves begins with a constellation one can see in the sky: “Twenty-one thousand light-years away, in the constellation of Aquila, a pair of stars are locked in a dance to the death,” she writes. Radio astronomers, Chapman points out, can tell that these twin neutron stars — stars that have gone supernova and collapsed into dense spheres — are causing waves in spacetime.

As it flows, “The Echoing Universe” also makes strange science familiar by connecting it to Earth — pointing out, for example, that the antenna in every cellphone doesn’t just detect texts but also faint signals from the universe (no notifications for those).

Chapman’s analogies are earthly and humorous. In discussing how radio waves cut through cosmic dust and allow astronomers to see behind it, she brings up chores: “There are two ways to approach the problem of dust at home. One is to wage a constant war by spending hours sweeping and polishing, much like the efforts of optical astronomers who painstakingly clean their data of the effects of dust in the hope of seeing starlight. The second way is to look at dust with different eyes and learn to not care that it’s there.”

That’s the radio astronomy way.

Some of radio astronomy’s earthly connections are a bit darker. Most notably, radar developments during World War II spurred the field forward. “Once released back into civilian life following the end of war, these newly anointed radar physicists had some time to consider how to apply this new knowledge,” Chapman writes. “More than a few looked up and wondered how radar could further our knowledge of astronomy.”

Bernard Lovell, one of those radar experts, repurposed the equipment he’d used in conflict and accidentally discovered that he could detect meteor showers.

Meanwhile, Puerto Rico’s Arecibo Telescope, built in the 1960s, came into existence not because of grand cosmic ambition but because such a large antenna was useful for detecting missiles. “$10 million for a nuclear threat detection system is one thing, but I doubt there would have been such ready funding available to probe the shadows of Mercury,” Chapman writes, although it eventually did do the latter.

Arecibo required big money and complex plans. But many facilities are humbler. As with Lovell’s repurposed equipment and Jansky’s tangles, plenty of pioneers made it up as they went. An amateur tinkerer named Grote Reber made the first radio map of the Milky Way in the 1940s using a telescope he built in his mother’s Wheaton, Illinois, backyard. His materials? Wood and galvanized metal from the hardware store, a crane’s wheels, and the rear axle of a Ford Model T, Chapman writes.

But radio telescopes — regardless of whether they’re as big as Arecibo or as scrappy as Reber’s — don’t produce dramatic pictures like the Hubble Space Telescope. “Instead of striving for high-resolution images comparable to what optical telescopes can give, radio astronomers strip away the glitter and graphics to get to the raw data that describes the whole story,” Chapman writes, calling it “8-bit” astronomy.

While Chapman paints a mostly nuanced, well-researched portrait of the field, her account is occasionally soft-focused by the kind of optimism common to space insiders. The chapter on Mars, for instance, positions the Red Planet as humans’ for-sure next home. “It’s a real fixer-upper,” she writes, “but hey, we’re getting desperate. With Earth’s growing crises, moving to Mars is no longer the distant dream it once was.” Modern Mars, however, requires more fixing up than even an extremely climate-ravaged Earth.

Similarly, she’s not just optimistic but certain about the existence of intelligent aliens. “Absolutely. I have no doubts at all,” she tells audiences at her public talks, according to the book.

“There is little controversy amongst astronomers,” she writes, given the size of the universe, the number of planets, and the number of chances life would have had to arise. But there is, in fact, controversy among other scientists, including some astronomers, and having no doubts about something for which there no data is not very scientific.

The heart of the book, though, is driven more by persuasive awe than overly rosy ideas, showing the reader the universe’s strange parts and the inventive humans who seek them out. Near the end, Chapman talks about the fall of the Arecibo Telescope, whose infrastructure collapsed in 2020; it won’t be repaired. On a trip there, Chapman stood underneath the structure. “I looked up and the antenna was gone,” she writes. “I saw only an uninterrupted expanse of sky, serenely drifting on as if nothing had happened.”

She was, in that moment, her own telescope.

And even though she couldn’t detect them, and neither could Arecibo anymore, radio waves were bombarding her.

“Some carry news, some carry messages from loved ones,” she writes. “Some have escaped black holes, some are the echoes from asteroids. Some have even travelled to us from the Era of the First Stars. It’s all there.”

And thanks to hardware stores, tinkerers, and accidents, radio astronomers have helped earthlings see that, even if they can’t see it.

This article was originally published on Undark. Read the original article.

Previously Published on undark.org

Join The Good Men Project as a Premium Member today.

All Premium Members get to view The Good Men Project with NO ADS.  A complete list of benefits is here.